Enabled by the OIF NNI
E-NNI I-NNI Core
Multiple Control Domains
Each domain could be a core, regional, or metro network.
The control inside each domain is independent:
• Different signaling control systems (e.g., proxy) with
different protocols (e.g., PNNI, CR-LDP, RSVP, etc.)
• Different routing control systems (e.g., centralized or
distributed) with different protocols (e.g., PNNI, OSPF, IS-IS,
• Different protection and restoration mechanisms.
• Different EMS/NMS
• Use UNI or NMI to initialize and/or terminate connection
• Different addressing scheme and/or space inside domain.
Implementation agreement on E-NNI between domains
provides end-to-end services that are transparent to users.
Sub-network Organization and Routing Areas
NNI Routing – Requirements
Accept ITU-T G.7715 routing requirements,
architecture and terminology.
Scope of routing area is a consequence of sub-
network organization that is described in G.805 at a
Subdivision of the network into routing areas where
the areas can contain smaller areas. This creates
4 levels of routing hierarchy is required by carriers
(OIF NNI requirement).
Interoperability between adjacent routing areas is
domain-domain routing protocol based on a
hierarchical link state protocol.
and Routing Controller
Abstract TE links Abstract TE links
Centralized routing control Distributed routing control
Centralized routing control
Separation of transport plane and control plane:
• Separated address space for routing controller and
• Separated topology for routing controller and
Routing control could be centralized or distributed.
Transport sub-network could be abstracted to be
one node or several border nodes with abstract
Transport routing’s main function is to provide path
computation to Connection Management (Control
plane). In hierarchical routing, the path is
computed at certain routing level.
Network Call Controller
Domain A Domain B Domain C
UNI E-NNI E-NNI UNI
UNI Sub-network NNI Sub-network NNI Sub-network UNI
Segment Segment Segment Segment Segment Segment Segment
Separation and Call Segments
Call model is part of ASON architecture (G.8080), G7713 and
In a multiple control domain environment, the end-to-end call
is achieved by concatenating multiple individual UNI, sub-
network and NNI call segments.
Each call segment could have multiple connections
associated with it (e.g., 1+1 path protection, virtual
Network call controllers and connection controllers are
defined in G.8080 and used in the NNI signaling specification.
• NNI call controller is responsible for associating the call
segments of NNI and sub-network
• NNI connection controller is responsible for signaling
NNI Application – Domain Based Recovery
Call/connection separation and call segmentation by ENNI
enables domain based protection and restoration
ENNI can be used to separate rerouting (recovery) domain.
Each rerouting domain contains one or more than one call
segment (A rerouting domain may contain other rerouting
Each rerouting domain could have its own protection
mechanism, e.g., liner protection on ENNI link, APS protection
inside one domain, and 1+1 path protection in another
The call controller at ingress ENNI performs redial function in
the scope of rerouting domain.
The failure happens in one domain would not cause
connection teardown in other domains.